Micro-source Characteristics And The Influence Of Which On Micro-grid Stability And Power Quality

With the increase of traditional energy sources depletion and environmental pollution, new energy has become an important way to solve the current crisis, wind and solar power is one of the important directions. A micro-grid system which was made of distributed generation, the energy storage device and AC loads becomes a hot research issue. The characteristics of micro-source which affect the stable operation of micro-grid and power quality should be taken more attention and need to study the corresponding improvement measures. The output power fluctuation of photovoltaic power generation systems, wind power system and other distributed generators is the main factor affects the stable operation of the system. Micro-source will cause harmonic pollution on the micro-grid through a large number of power electronic devices access to system.In this thesis, the random models of wind, solar power are described in detail. The photovoltaic power system and wind power system two typical micro-sources access to systems approach are studied. Finally, a mathematical model of micro-grid in islanding operation is studied and made some relevant analysis.In order to study effects for micro-grid voltage stability of different characteristics of micro-source. Similar to traditional power generation systems, voltage stability of micro-grid in islanding operation is a prerequisite for reliable operation. Analysis of micro-grid islanded operation based on voltage stability, effect of micro-sources for micro-grid voltage stability was studied. Micro-source output power instability leading to DC side voltage fluctuation caused by load side voltage instability and done some relevant simulation analysis. According to system voltage instability, this thesis mainly studies the storage devices and the related control strategies to improve the system voltage stability.The influence of the micro-source characteristics on the system power quality, through the access and topological structure of micro-source. And the thesis analyzed the voltage fluctuation, voltage deviation and the other power quality which produced by the access of the micro-sources.Then the thesis mainly described the topological structure of the photovoltaic power system and wind power generation system and the influence of the topological structure on system power quality. Finally, the thesis considered the improvement of micro-grid power quality environment, proposed the grid connected inverter with APF function, established its small signal model, analyzed the harmonic current detection method and current control method.